(a) An official sample shall be taken by a veterinarian of at least four horses chosen by lot in every weight class. Each horse entering each weight class shall be identified by number. Numbers shall be drawn by lot until at least four horses are designated for official sampling.

(b) The veterinarian or any judge may also require that an official sample be taken of any horse not included in the selection specified in subdivision (a) of this section, if in his or her opinion such a sample is necessary to assure the integrity of the testing program.

(c) Each official sample shall be submitted by the veterinarian to a laboratory for a test. Test results disclosing the presence of drugs shall be forwarded to the director who shall notify the fair concerned and shall give written notice thereof by regular mail, personal service or certified mail to the owner and the person having care, custody or control of the horse.